1. Field of the Invention
This invention relates generally to a continuous free flow electrophoresis device and, more particularly, to an easily sterilizable electrophoresis device which can be used at 0 or 1 g.
2. Description of the Prior Art
Free flow electrophoresis is a process in which a sample stream is introduced into a liquid buffer flow within a separation column. A fixed or varying electric field is maintained across the separation column perpendicular to the buffer flow. Species of virtually identical biomolecules often have different surface electrical charges and thus react or move differently within electric fields. Passing a selected sample of biomolecules or bioparticles through an electric field in an appropriate buffer or carrier results in the molecules migrating to separate positions in the electrical field representative of their charge. Thus, visually and chemically similar biomolecules can be separated into subspecies according to their electric charge. Individual components in the sample stream are separated from each other on the basis of their mobility in the imposed electric field and are collected at the exit of the separation column in one or several collection vessels.
Contamination of the sample and buffer has been a constant problem with conventional electrophoresis devices. To help reduce this contamination problem, investigators commonly operate conventional electrophoresis devices at about 4.degree. C. to reduce the chances of opportunistic organism growth. However, not all separations may be desirable at this low temperature. Furthermore, large cooling systems are required to maintain these low operating temperatures. To help eliminate this contamination problem, it would be helpful to be able to sterilize the electrophoresis device. However, conventional electrophoresis devices are not generally sterilizable due to the fact that they are constructed as a single liquid flow and electrical control unit which is not easily disassembled. Further, many conventional electrophoresis devices use polycarbonate based separation plates and membranes which are subject to surface cracking, known as "crazing", when subjected to typical sterilization temperatures of about 250.degree. F.
With the advent of the space shuttle program, a need has arisen for a continuous flow electrophoresis apparatus which is capable of functioning in the gravity free environment of space as well as in a ground based laboratory. Due to the duration of space shuttle flights, an onboard electrophoresis device, and in particular the buffer flow loop, would need to be sterilized prior to flight to prevent contamination and biological growth occurring in the device during extended space flight. Therefore, a continuous flow electrophoresis device for use in space should be easily sterilizable by conventional means, such as autoclaving. Typical autoclaves operate at 250.degree. F. Hence, the electrophoresis device should be capable of withstanding this sterilization atmosphere for at least 35 minutes to achieve complete sterilization. This sterilization capability would also be useful for terrestrial use of an electrophoresis device by allowing rapid sterilization of the device between runs of toxic or infectious samples and by significantly lowering the possibility of contamination from undesirable organisms or their byproducts. The ability to quickly and easily sterilize the electrophoresis device would also allow separations to be conducted at elevated temperatures and would reduce the need for large and costly cooling systems.
Further, conventional electrophoresis devices rely on gravity in the collection of sample fractions. Obviously, a gravity flow collection system would be totally inadequate for space flight. Therefore, a non-gravity dependent collection system is imperative for any space flight electrophoresis apparatus.
Therefore, it is an object of the invention to provide a continuous flow electrophoresis device which may be easily partially disassembled and sterilized in an autoclave.
Further, it is an object of the present invention to provide a sample collection system capable of collecting and storing electrophoresis fractions in 0 or 1 g.